Index: sys/netinet/tcp_hostcache.h
===================================================================
--- sys/netinet/tcp_hostcache.h
+++ sys/netinet/tcp_hostcache.h
@@ -56,7 +56,7 @@
 	uint32_t	rmx_mtu;	/* MTU for this path */
 	uint32_t	rmx_ssthresh;	/* outbound gateway buffer limit */
 	uint32_t	rmx_rtt;	/* estimated round trip time */
-	u_long		rmx_rttvar;	/* estimated rtt variance */
+	uint32_t	rmx_rttvar;	/* estimated rtt variance */
 	u_long		rmx_cwnd;	/* congestion window */
 	u_long		rmx_sendpipe;	/* outbound delay-bandwidth product */
 	u_long		rmx_recvpipe;	/* inbound delay-bandwidth product */
Index: sys/netinet/tcp_hostcache.c
===================================================================
--- sys/netinet/tcp_hostcache.c
+++ sys/netinet/tcp_hostcache.c
@@ -542,8 +542,8 @@
 	        if (hc_entry->rmx_rttvar == 0)
 			hc_entry->rmx_rttvar = hcml->rmx_rttvar;
 		else
-			hc_entry->rmx_rttvar =
-			    (hc_entry->rmx_rttvar + hcml->rmx_rttvar) / 2;
+			hc_entry->rmx_rttvar = ((uint64_t)hc_entry->rmx_rttvar +
+			    (uint64_t)hcml->rmx_rttvar) / 2;
 		TCPSTAT_INC(tcps_cachedrttvar);
 	}
 	if (hcml->rmx_ssthresh != 0) {
@@ -624,7 +624,7 @@
 			    hc_entry->rmx_ssthresh,
 			    msec((u_long)hc_entry->rmx_rtt *
 				(RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
-			    msec(hc_entry->rmx_rttvar *
+			    msec((u_long)hc_entry->rmx_rttvar *
 				(RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))),
 			    hc_entry->rmx_cwnd,
 			    hc_entry->rmx_sendpipe,
Index: sys/netinet/tcp_var.h
===================================================================
--- sys/netinet/tcp_var.h
+++ sys/netinet/tcp_var.h
@@ -405,7 +405,7 @@
 	uint32_t	rmx_mtu;	/* MTU for this path */
 	uint32_t	rmx_ssthresh;	/* outbound gateway buffer limit */
 	uint32_t	rmx_rtt;	/* estimated round trip time */
-	u_long		rmx_rttvar;	/* estimated rtt variance */
+	uint32_t	rmx_rttvar;	/* estimated rtt variance */
 	u_long		rmx_cwnd;	/* congestion window */
 	u_long		rmx_sendpipe;   /* outbound delay-bandwidth product */
 	u_long		rmx_recvpipe;   /* inbound delay-bandwidth product */